Question

The cost of painting the outer curved surface of a cylinder at rs 0.75 per cm^2 is rs 165. If the height of the cylinder is 1m

Answer 1

Question - The cost of painting the outer Curved surface of a cylinder at rs 0.75 per cm² is rs 165. If the Height of the cylinder. Find the radius of its base.

Solution:-

we know that curved surface area of cylinder = 2πrh

Given :- Height = 1m => 100cm

Cost of painting = Rs 0.75

Total cost = Rs 15

= 2πrh × 0.65 = 165

= 2× 22 × r × 100× 0.75 /7 = 165

= r = 7/ 20cm

=> r = 0.35 cm

Answer 2

Correct Question:

• The cost of painting the outer curved surface of a cylinder at rs 0.75 per cm^2 is rs 165. If the height of the cylinder is 1m , find the Radius of its base.

Answer:

$\large\bold\red{Radius=0.35\:cm}$

Step-by-step explanation:

Given,

A cylinder having,

• Height, h = 1m = 100 cm

Let,

• Radius of base = r
• Curved surface area = a

Now,

We know that,

$c = 2\pi rh$

Therefore,

We get,

$= > c = 2 \times \pi \times 100 \times r\\ \\ = > c = 200\pi \: r$

Now,

Cost of painting @ ₹ 0.75 / cm^2 = 165

Therefore,

We get,

$= > 200\pi \: r\times 0.75 = 165 \\ \\ = > r = \dfrac{165}{200\pi \times 0.75} \\ \\ = > r = \dfrac{165 \times 100 \times 7}{200 \times 22 \times 75} \\ \\ = > r= \dfrac{165 \times 7}{44 \times 75} \\ \\ = > r = \dfrac{11 \times 7}{44 \times 5} \\ \\ = > r = \dfrac{7}{4 \times 5} \\ \\ = > r = \dfrac{7}{20} \\ \\ = > \bold{r= 0.35 \: cm}$